Several serological studies stated evidences that elevated leptin concentration in serum is correlated with breast cancer risk and counted it as an independent risk factor, in addition to its involvement in many malignancy stages including as cell growth, invasion, migration, metastases, recurrence and therapy response in some organs such as liver [17], lung [18], stomach [19], thyroid [20], uterus [12], colon [21]. The gene discussed is LEP; the disease is breast cancer.